After the flood waters recede, Father Hemmings wanders the beach. He notices a being lying on the shore. He thinks it is a fallen angel, and brings it back to his church, St Anthony's, to give it Last Rites.
The Doctor and Peri land on Canvey Island and attend a church service. After the service, they are welcomed by Father Hemmings. He invites them to join the ladies outside for coffee. However, the Doctor notices that his celery has gone limp, and heads back to the TARDIS to investigate.
Peri talks to an old woman named Agatha, who tells her that Marjory Kennedy was murdered by Walter Seacombe, though his father gave him an alibi. Walter killed Marjory because she had an affair with Hemmings. Marjory's mother started turning the town against Father Hemmings the day he went to the hospital to give Marjory her Last Rites.
The Doctor returns, and Agatha leaves them. He tells Peri that he has detected alien radiation and is going to snoop around a bit. Peri decides to follow Mrs Kennedy and ask her about Marjory, but Mrs Kennedy goes into her house and won't answer the door. Someone else sees Peri and offers to tell her about Marjory. It is Walter Seacombe, and Peri is a little afraid to be alone with him. He tells her he killed Marjory because she didn't want him to be a father to her baby. He starts crying, and Peri leaves and returns to the TARDIS on the beach. She finds the Doctor more concerned about the radiation than the townspeople's troubles.
Suddenly they see Father Hemmings on the beach. He brushes them off, and finds another "angel", bringing it to the church. While he is on the beach, the Doctor and Peri search the church. Peri, going through Hemmings' diary, finds no mention of him giving Marjory Last Rites. The Doctor has found the crypt, and they enter it. They find dead aliens in the crypt, whose bodies are giving off the radiation when they dry out from the soaking in the sea. They realise that Hemmings is giving Last Rites to the aliens.
Hemmings returns, carrying another alien, and they hide. Hemmings finds them when the Doctor's radiation device makes an alarming sound. The Doctor tries to convince Hemmings that the beings are not angels, but rather aliens who are releasing dangerous radiation. Hemmings isn't swayed by the Doctor's arguments, but Peri realises that he must have blamed Marjory for the baby's death, so he didn't give her Last Rites. Peri tells him she forgives him, and he lets them take the alien bodies.
- Canvey Island is in Essex.
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